PolyE-IL: A polymeric Brønsted acid ionic liquid catalyst for catalytic thermo liquefaction of sugarcane bagasse into carboxylic acids

The present study demonstrates a catalytic thermo liquefaction (CTL) process for the liquefaction of sugarcane bagasse into carboxylic acids using recyclable polymeric Brønsted acid ionic liquids (PolyE-ILs) catalyst. A series of acid catalysts such as mineral acids, imidazole-based ionic liquid and PolyE-ILs with variable counter ions were tested. Of the tested catalysts, [PEI]⁺[HSO₄]⁻ resulted in 51.84% levulinic acid, 53.07% formic acid and 100% acetic acid yields compared with their theoretical maximum with 81.40% feedstock conversion at 210 °C for 120 min. Under 10 bar N₂ pressure. The carbon-enriched side products (CTL-oil), catalyst and carboxylic acids were separated by integrating the adsorption and membrane separation process with >98% efficiency. The CTL-oil with calorific a value of 25–26 MJ/kg can be explored for further energy and fuel applications. Thus, the use of a robust and recyclable catalyst at moderate operating conditions provides an efficient pathway for the valorization of sugarcane bagasse into carboxylic acids and CTL-oil.